Insulating plate, insulating plate manufacturing method and terminal block

ABSTRACT

An insulating plate ( 20 ) made of synthetic resin for transferring heat transferred from conductors to nuts ( 10 ) to a heat sink ( 40 ) is provided with nut accommodating recesses ( 21 ) for accommodating the nuts ( 10 ). Each nut accommodating recess ( 21 ) includes a bottom plate ( 22 ) to be sandwiched between the nuts ( 10 ) and the heat sink ( 40 ) and a surrounding wall ( 23 ) vertically extending from the bottom plate ( 22 ) to surround the side surface of the nut ( 10 ). The surrounding walls ( 23 ) are provided with first and second pressing surfaces ( 28, 29 ) to be pressed by ejector pins ( 83 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an insulating plate, an insulating platemanufacturing method and a terminal block.

2. Description of the Related Art

Japanese Unexamined Patent Publication No. 2008-98007 discloses aterminal block for electrically connecting conductors, such as busbars,extending from electrical devices, such as a motor and an inverter. Thisterminal block electrically connects the conductors by placing theconductors of the respective electrical devices one above another onmetal nuts insert molded in a terminal block main body and fastening theconductors by tightening bolts and the nuts.

The electrical devices generally generate high levels of heat and causethe conductors to become hot. Hence, a metal heat sink is arranged belowthe nuts via an insulating member in the form of a flat plate made ofsynthetic resin. Heat transferred from the conductors to the nuts istransferred to the heat sink via the insulating member and is radiatedfrom the heat sink in the terminal block.

Attempts have been made to form the insulating member with recesses toaccommodate the nuts. More particularly, a mold is provided with moldpins for forming the recesses. However, a resin molded article, such asthe insulating member, generally contracts when being separated from themold, and it is difficult to separate the resin molded article from themold due to the mold pins fit in the recesses. Thus, the insulatingmember is separated from the mold by ejector pins that push the bottomsurfaces of the recesses. However, the ejector pins leave slight indentson the bottom surfaces of the recesses. The indents caused by theejector pins result in air layers between the lower surfaces of the nutsand the bottom surfaces of the recesses. These air layers have lowerthermal conductivity than metals, synthetic resins and the like. As aresult, heat is not transferred as efficiently from the nuts to the heatsink, thereby reducing heat radiation performance. This phenomenon alsocould occur on a boundary surface between the insulating member and theheat sink.

The present invention was completed in view of the above situation andan object thereof is to improve heat radiation performance of a terminalblock.

SUMMARY OF THE INVENTION

The invention relates to an insulating plate made of synthetic resin fortransferring heat from at least one conductor extending from a device toat least one nut and further to a heat sink. The insulating plate has atleast one nut accommodating recess for accommodating the respective nut.The nut accommodating recess includes a base plate to be sandwiched inclose contact between the nut and the heat sink and at least onesurrounding wall extending from the bottom plate to at least partlysurround the side surface of the nut. The surrounding wall has at leastone pressing portion to be pressed by at least one ejector pin used toseparate the nut accommodating recess from a mold pin when the innersurface of the nut accommodating recess is formed.

According to the thus constructed, the pressing portion that is pressedby the ejector pin is on the surrounding wall and not on the bottomplate that is to be held in close contact with the nut. Thus, the nutaccommodating recess can be separated from the mold pin without formingan indent on the bottom plate. As a result, an air layer with lowthermal conductivity is not formed between the nut and the base plate.In this way, the nut closely contacts the base plate, so that heat canescape more easily from the nut to the heat sink via the insulatingplate and heat radiation performance of the terminal block can beimproved.

A plurality of pressing portions may be formed intermittently on thesurrounding wall. Accordingly, a pressing force of the ejector pin isdistributed among the pressing portions when the nut accommodatingrecess is separated from the mold pin. This can prevent deformation ofthe insulating plate when the insulating plate is separated from themold.

The pressing portion may be on an end portion of the surrounding wallopposite to the bottom plate. Accordingly, a separate pressing portionis not needed on the surrounding wall. Therefore, the insulating plateis small and has a simple structure.

Positioning ribs may be provided on the inner surface of the surroundingwall and may extend in a direction away from the bottom plate. Thepositioning ribs are dimensioned to contact the side surfaces of thenut.

The positioning ribs may be formed to reinforce the surrounding wallover substantially the entire height.

The inner peripheral shape of the surrounding wall may substantiallyconform to the outer peripheral shape of the nut.

A plurality of nuts may be accommodated in a nut accommodating recess;and at least one partition wall may be provided between the nuts so thatthe nuts.

The partition wall may extend higher than the conductors placed on thenuts. More particularly, a height of the partition wall may be more thanabout 1.5 times the height of outer surrounding walls standing up fromthe bottom plate of the nut accommodating recess.

The heat sink may be positioned with respect to a mold by inserting apositioning projection of the mold into a recess formed in the heatsink.

The synthetic resin used for molding the insulating plate may have acontent of glass and talc of between about 50% and about 75%.

The invention also relates to a terminal block with an integrally formedmolded resin part that holds insulating plate, the nut and the heat sinkin close contact. Thus, a heat radiation performance of the terminalblock can be improved.

The present invention is preferably embodied to have the followingconstructions.

The nut may be disposed in the nut accommodating recess when molding themolded resin part to position the nut with respect to the insulatingplate.

These and other objects, features and advantages of the invention willbecome more apparent upon reading the following detailed description ofpreferred embodiments and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a terminal block.

FIG. 2 is a plan view of the terminal block.

FIG. 3 is a rear view of the terminal block.

FIG. 4 is a bottom view of the terminal block.

FIG. 5 is a section along V-V of FIG. 2.

FIG. 6 is a section along VI-VI of FIG. 2.

FIG. 7 is a plan view of a nut.

FIG. 8 is a plan view of an insulating plate.

FIG. 9 is a rear view of the insulating plate.

FIG. 10 is a bottom view of the insulating plate.

FIG. 11 is a plan view of a heat sink.

FIG. 12 is a bottom view of the heat sink.

FIG. 13 is a side view showing a state before the nuts, the insulatingplate and the heat sink are assembled.

FIG. 14 is a plan view showing a state after the nuts, the insulatingplate and the heat sink are assembled.

FIG. 15 is a section along XV-XV of FIG. 14.

FIG. 16 is a section showing a terminal block molded in first and secondblock molds.

FIG. 17 is a perspective view with a section showing the insulatingplate is separated from first and second molds.

FIG. 18 is a section showing nut accommodating recesses are fitted tothe first mold.

FIG. 19 is a section showing the insulating plate separated from thefirst mold.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A terminal block in accordance with the invention is to be mounted in amotor case to be installed in a vehicle such as an electric vehicle or ahybrid vehicle and is provided to electrically connect a busbar of afirst electric equipment such as an electric motor (e.g. a three-polebusbar provided in a three-phase alternating current motor) and a busbarof a second electric equipment such as an inverter (e.g. a three-polebusbar provided in an inverter).

The terminal block includes nuts 10 with upper and lower surfaces.Unillustrated busbars extending from electrical devices are to be placedon the upper surfaces of the nuts 10 and a heat sink 40 is arrangedadjacent to the lower surfaces of the nuts 10. An insulating plate 20 issandwiched between the nuts 10 and the heat sink 40. A molded resin part60 made e.g. of synthetic resin at least partly covers the nuts 10, theinsulating plate 20 and the heat sink 40. In the following description,a vertical direction is based on a vertical direction in FIG. 5 and alateral direction is based on a lateral direction in FIG. 2.

Each nut 10 is a substantially rectangular metal block with roundedcorners, as shown in FIGS. 7 and 13, and has upper and lower fasteningsurfaces 10A and 10B. A bolt tightening hole 11 penetrates a centralpart of each nut 10 in a vertical direction that is perpendicular toboth fastening surfaces 10A, 10B. Unillustrated busbars are placed onthe upper fastening surface 10A of the nut 10 and an unillustrated boltthen is screwed into the bolt tightening hole 11 for electricallyconductively connecting the busbars.

A step 12 is formed on the outer peripheral edge of an upper end of thenut 10. This step 12 is formed to be slightly lower than the upperfastening surface 10A of the nut 10, as shown in FIG. 5. The step 12 isprovided over substantially the entire outer peripheral edge of the nut10 and is parallel to the upper and lower fastening surfaces 10A, 10B ofthe nut 10. Note that the upper and lower fastening surfaces 10A, 10Band the step 12 of the nut 10 are flat without irregularity.

The insulating plate 20 is made of an insulating material such, assynthetic resin, and, is long in the lateral direction, as shown in FIG.8. The insulating plate 20 functions to transfer heat of the busbarsplaced on the nuts 10 from the nuts 10 to the heat sink 40 located belowthe nuts 10. Note that the synthetic resin preferably has a content ofglass and talc of between about 50% and 75% (e.g. about 66%). Thus,warping is less likely to occur after molding and thermal conductivityis high as compared to synthetic resin having a content of glass andtalc of about 33%. This enables heat to be transferred efficiently fromthe nuts 10 to the heat sink 40.

Nut accommodating portions 21 are arranged substantially side by side inthe lateral direction of the insulating plate 20 and are capable ofaccommodating the respective nuts 10. The nut accommodating portions 21function as first positioning means for accommodating the nuts 10.

As shown in FIG. 5, each nut accommodating portion 21 includes a bottomplate 22 for closely contacting the lower fastening surface 10B of thenut 10 and a surrounding wall 23 that projects up from the bottom plate22 to surround side surfaces of the nut 10 over substantially the entireperiphery. Accordingly, the nut accommodating portion 21 has an openupper end with a rectangular shape having rounded corners. Further, asshown in FIG. 8, the respective nut accommodating portions 21 are formedsubstantially side by side so that longer sides are adjacent to eachother. The nut accommodating portions 21 located at the opposite sidesin the lateral direction are smaller nut accommodating portions 21A andlarger nut accommodating portions 21B are located in a central orintermediate part.

A single unitary bottom plate 22 is provided for all of the nutaccommodating portions 21, as shown in FIG. 10, and has flat upper andlower surfaces 22A, 22B. Thus, the upper surface 22A of the bottom plate22 can close contact the lower fastening surfaces 10B of the nuts 10 inthe nut accommodating portions 21, as shown in FIG. 5, without anyclearances between the nuts 10 and the bottom plate 22. In this way,heat can be transferred efficiently from the nuts 10 to the bottom plate22.

As shown in FIG. 8, the inner peripheral surfaces of the surroundingwalls 23 are substantially rectangular and substantially conform to theouter peripheral shapes of the nuts 10. Further, the inner peripheralsurfaces of the surrounding walls 23 are slightly larger than the outerperipheral surfaces of the nuts 10, so that small clearances existbetween the inner peripheral surfaces of the surrounding walls 23 andthe side surfaces of the nut 10 when the nuts 10 are accommodated in thenut accommodating portions 21 as shown in FIG. 14.

The surrounding wall 23 located between two adjacent nut accommodatingportions 21 is common to both nut accommodating portions 21 and definesa partition wall 24 partitioning the two nuts 10 in the nutaccommodating portions 21. A part of the surrounding wall other than thepartition wall 24 defines an outer surrounding wall 23A. As shown inFIG. 9, the height of the partition wall 24 is about twice the height ofthe outer surrounding walls 23A to ensure a creepage distance betweenthe two adjacent nuts 10. The partition walls 24 are higher than thebusbars placed on the upper fastening surfaces 10A of the nuts 10. Thus,the busbars cannot contact each other to be short-circuited due tolateral movements of the busbars placed on the nuts 10.

Pressing projections 27 project from the respective inner peripheralsurfaces of the outer surrounding walls 23A, as shown in FIG. 8, andhave a substantially having a rectangular or polygonal plan view. Moreparticularly, one pressing projection 27 is provided on the innerperipheral surface of each shorter side of the surrounding wall 23 ofthe each smaller nut accommodating recess 21A and two spaced apartpressing projections 27 are provided on the inner peripheral surface ofthe outer longer side of the surrounding wall 23 of the each smaller nutaccommodating recess 21A and the inner peripheral surface of the eachshorter side of the surrounding wall 23 of each larger nut accommodatingrecess 21B.

The pressing projections 27 extend substantially vertically and areformed over substantially the entire height of the outer surroundingwalls 23A. Thus, the upper end surfaces of the pressing projections 27are substantially flush with the upper end surfaces of the outersurrounding walls 23A as shown in FIG. 17. Further, the thickness ofparts where the pressing projections 27 are provided is larger than thethicknesses of the other parts of the outer surrounding walls 23A by thethickness of the pressing projections 27.

First pressing surfaces 28 are formed by the upper end of each pressingprojection 27 and the upper end of the outer surrounding wall 23A. Thefirst pressing surfaces 28 formed by the upper end of each pressingprojection 27 are substantially flush with and adjacent to the upper endof the outer surrounding wall 23A. The first pressing surfaces 28 formedby the upper end surfaces of the surrounding wall 23 and the pressingprojection 27 have substantially the same area.

As shown in FIG. 8, second pressing surfaces 29 are formed on the upperends of the partition walls 24 and have a rectangular plan view. Asshown in FIGS. 6 and 13, the second pressing surfaces 29 are formed byrecessing the partition walls 24 at opposite sides of a center of anupper end of each partition wall 24 in a long side direction.

Further, as shown in FIGS. 17 and 18, the first and second pressingsurfaces 28, 29 are to be pressed by ejector pins 83 provided in molds81, 82 when the insulating plate 20 is separated from the molds 81, 82after molding opening. Specifically, the insulating plate 20 is formedby the first mold 81 arranged at an upper side and the second mold 82arranged at a lower side. The first mold 81 forms a first an uppersurface of the insulating plate 20 and the second mold 82 forms a lowersurface of the insulating plate 20. The insulating plate 20 is formed byinjecting synthetic resin into a cavity formed by the first and secondmolds 81, 82, and is completed by being separated from the first andsecond molds 81, 82 after the synthetic resin is cured.

The nut accommodating recesses 21 of the insulating plate 20 are formedby accommodating-portion forming parts, such as mold pin 81A provided inthe first mold 81. The nut accommodating recesses 21 slightly contractwhen cooled and cured and fit to the accommodating-portion forming parts81A, as shown in FIG. 18. Therefore, it is difficult to separate the nutaccommodating recesses 21 from the mold. The ejector pins 83 in thefirst mold 81 address this problem and press the first and secondpressing surfaces 28, 29 so that the nut accommodating recesses 21 areseparated from the accommodating-portion forming parts 81A and theinsulating plate 20 is separated from the first mold 81 as shown inFIGS. 17 and 19. More particularly, the insulating plate 20 is separatedfrom the first mold 81 by pressing the first and second pressingsurfaces 28, 29 instead of the bottom plate 22, and is formed withoutleaving indents on the surface of the bottom plate 22. As a result,there will be no air layers having lower thermal conductivity thanmetals, synthetic resins and the like between the nuts 10 and the bottomplates 22. The insulating plate 20 is held in close contact with thenuts 10 and the bottom plate 22 to improve heat transfer from the nuts10 to the insulating plate 20.

Several first and second pressing surfaces 28, 29 are formedintermittently on the surrounding wall 23. Thus, forces of the ejectorpins 83 are distributed among the plurality of first and second pressingsurfaces 28, 29 so that the base plate 22 of the insulating plate 20 isprevented from being deformed when the insulating plate 20 is separatedfrom the first mold 81.

The first and second pressing surfaces 28, 29 are formed on respectiveparts of the upper end surfaces of the surrounding walls 23 and those ofthe partition walls 24. Thus, it is not necessary to form pressingsurfaces separately on the insulating plate 20 and it is possible tomake the insulating plate 20 smaller and simple.

Furthermore, the synthetic resin used for the insulating plate 20 has acontent of glass and talc of between about 50% and about 75% (e.g. about66%). Therefore, warping is less likely to occur after molding ascompared to synthetic resin having a content of glass and talc of about33%. This enables the bottom plate 22 of the insulating plate 20 to beheld more closely in contact with the nuts 20, and heat transfer fromthe nuts 10 to the bottom plate 22 is improved further.

Positioning ribs 25 are provided on the inner peripheral surface of thesurrounding wall 23 and project in to the nut accommodating portion 21so that projecting ends of the positioning ribs 25 can contact the sidesurfaces of the nut 10 accommodated in the nut accommodating portion 21.The positioning ribs 25 of the outer surrounding wall 23A extendsubstantially straight up from the bottom plate 22 and continue oversubstantially the entire height of the outer surrounding wall 23A. Thepositioning ribs 25 on the partition wall 24 extend substantiallystraight up from the bottom plate 22 to a substantially vertical centralof the partition wall 24.

As shown in FIG. 8, two spaced apart positioning ribs 25 are provided onthe inner surface at each of four sides of the surrounding wall 23 ineach smaller nut accommodating recess 21A. Further, two spaced apartpositioning ribs 25 are provided on the inner surface of each longerside of the surrounding wall 23 in each larger nut accommodating recess21B and three spaced apart positioning ribs 25 are provided on the innersurface of each shorter side thereof. The positioning ribs 25 on theouter longer sides of the surrounding walls 23 in the smaller nutaccommodating recesses 21A are formed laterally of the pressingprojections 27 and those on the shorter sides of the surrounding walls23 in the smaller nut accommodating recesses 21A are formed on thepressing projections 27. Further, two of the positioning ribs 25 on eachshorter side of the surrounding wall 23 in each larger nut accommodatingrecess 21B are laterally of side surfaces of the pressing projections27. In this way, the nuts 10 accommodated in the nut accommodatingrecesses 21 are positioned accurately by a plurality of positioning ribs25 as shown in FIG. 14.

A substantially cylindrical bolt escaping recess 26 extends down into asubstantially central part of the upper surface 22A of the bottom plate22 in each nut accommodating portion 21, as shown in FIGS. 5 and 8-10.Each bolt escaping recess 26 has a cylindrical side wall and a bottomwall that have thicknesses substantially equal to the thickness of thebottom plate 22. As shown in FIGS. 9 and 10, each bolt escaping recess26 has a substantially has a cylindrical outer surface projecting downfrom the lower surface 22B of the bottom plate 22.

As shown in FIG. 5, the bolt escaping recesses 26 are substantiallycoaxial with the respective bolt tightening holes 11 of the nuts 10 andhave inner diameters slightly larger than the bolt tightening holes 11.Thus, the nut 10 will not interfere with the bottom plate 22 of theinsulating plate 20 and the insulating plate 20 will not be broken bythe bolt as the bolt is screwed into the nut 10 and inserted through thebolt tightening hole 11.

The heat sink 40 is shown in FIG. 11 and is produced of a materialhaving a higher heat capacity than the remaining parts of the terminalblock, such as die-cast aluminum. The heat sink 40 includes a sink mainbody 41 on which the insulating plate 20 is to be placed, and a fixingportion 42 unitary with the sink main body 41. The sink main body 41 islaterally long and the fixing portion 42 projects from one longer sideedge of the sink main body 41.

The insulating plate 20 is to be placed on an upper surface 41A of thesink main body 41. Further, the upper surface 41A of the sink main body41 is flat and/or polished to have no irregularities. This enables thelower surface 22B of the bottom plate 22 of the insulating plate 20 andthe upper surface 41A of the sink main body 41 to be held in closecontact with the insulating plate 20 placed on the upper surface 41A ofthe sink main body 41 as shown in FIG. 5.

The sink main body 41 is formed with five accommodation recesses 43arranged at substantially equal intervals in the lateral direction. Theaccommodation recesses 43 define substantially circular openings in theupper surface 41A of the sink main body 41 and are bottomed recessesthat extend down into the upper surface 41A of the sink main body 41, asshown in FIG. 5. The accommodation recesses 43 are formed so that thebolt escaping recesses 26 of the insulating plate 20 can nest therein.More particularly, the bolt escaping recesses 26 are fit in theaccommodation recesses 43 with small clearances between the outersurfaces of the bolt escaping recesses 26 and the inner peripheralsurfaces of the accommodation recesses 43. Thus, the insulating plate 20and the heat sink 40 can be assembled and positioned with respect toeach other by fitting the bolt escaping recesses 26 of the insulatingplate 20 into the corresponding accommodation recesses 43.

An outer edge step 44 is formed at the outer peripheral edge of a lowerend of the sink main body 41 and is above the lower surface of the sinkmain body 41. As shown in FIG. 12, this outer edge step 44 is formedover all of the outer peripheral edge except at a connected part of thesink main body 41 to the fixing portion 42.

The fixing portion 42 is laterally long along the side surface of thesink main body 41. Bolt insertion holes 42A vertically penetrateopposite lateral sides of the fixing portion 42. Substantiallycylindrical projections 45 extend vertically from the upper surface ofthe fixing portion 42. As shown in FIG. 6, the cylindrical projections45 are connected to the side surface of the sink main body 41 facing thefixing portion 42, and extend up to a position slightly above the uppersurface 41A of the sink main body 41. Each cylindrical projection 45defines a bottomed recess with an open upper end, as shown in FIG. 11.

As shown in FIG. 12, recesses 46 are formed in the lower surfaces of thesink main body 41 and/or the fixing portion 42. The recesses 46 form atleast one heat radiation fin 46A in the fixing portion 42, and coolingwater or fluid may be circulated to contact the fin 46A. The recess 46and the heat radiation fin 46A increase the surface area of the lowersurface of the heat sink 40 and thus improve a heat radiation propertyfrom the heat sink 40.

The molded resin part 60 is made unitarily e.g. of synthetic resin and,as shown in FIGS. 1, 3 and 5, partly covers the nuts 10, the insulatingplate 20 and the heat sink 40 that have been assembled with each other.The molded resin part 60 includes an upper cover 61 that closelycontacts the steps 12 of the nuts 10 and the upper ends of thesurrounding walls 23 of the insulating plate 20, a lower cover 62 thatclosely contacts the outer edge step 44 of the heat sink 40, and a sidewall 63 that closely contacts the insulating plate 20 and the outer sidesurfaces of the sink main body 41 of the heat sink 40. Thus, the sidewall 63 unitarily joins the upper and lower covers 61, 62.

As shown in FIG. 5, the upper cover 61 includes nut covers 61A thatcover the outer peripheral edges of the steps 12 of the respective nuts10 over substantially the entire peripheries and surrounding wall covers61B that cover the upper ends of the surrounding walls 23 except atparts of the partition walls 24. The nut covers 61A and the surroundingwall covers 61B are formed unitarily. Note that the parts of thepartition walls 24 are exposed at the upper end surfaces of thesurrounding wall covers 61B.

As shown in FIGS. 4 and 5, the lower cover 62 covers the outer edge step44 of the sink main body 41 of the heat sink 40 over the entire rangefrom below. In this way, the molded resin part 60 vertically sandwichesthe nuts 10, the insulating plate 20 and the heat sink 40 and hold therespective members 10, 20 and 40 in close contact with each other, asshown in FIGS. 5 and 6.

The upper cover 61 also substantially fills the clearances between theinner peripheral surfaces of the surrounding walls 23 of the nutaccommodating portions 21 and the side surfaces of the nuts 10, therebyimproving a degree of adhesion between the molded resin part 60, thenuts 10 and the insulating plate 20.

As shown in FIGS. 3 and 5, the side wall 63 entirely covers the sidesurfaces of the insulating plate 20 and the side surfaces of the sinkmain body 41 of the heat sink 40 between the upper and lower covers 61and 62. As shown in FIG. 6, the side wall 63 has projection covers 63Athat cover the cylindrical projections 45 of the heat sink 40. Theprojection covers 63A fill up the interiors of the cylindricalprojections 45 and entirely cover the upper and side surfaces of thecylindrical projections 45, thereby improving a degree of adhesionbetween the molded resin part 60 and the heat sink 40.

The terminal block is assembled by initially placing the nuts 10 in therespective nut accommodating portions 21 of the insulating plate 20 andfitting the bolt escaping recesses 26 of the nut accommodating portions21 into the respective accommodation recesses 43 of the heat sink 40.The nuts 10, the insulating plate 20 and the heat sink 40 that have beenassembled, as shown in FIGS. 14 and 15, then are set in first and secondmolds 71, 72. The properly positioned nuts 10, insulating plate 20 andheat sink 40 can be set in the first and second molds 71, 72 withoutbeing displaced. The surfaces of the insulating plate 20 do not haveeven small irregularities. Thus, the upper and lower surfaces 22A and22B of the bottom plate 22 closely contact the lower fastening surfaces10B of the nuts 10 and the upper surface 41A of the sink main body 41 ofthe heat sink 40.

Further, the steps 12 of the nuts 10 are pressed over the entireperipheries from above by resin engaging portions 73 in the first blockmold 71 and the lower surface of the heat sink 40 is supported by thesecond block mold 72. Thus, the bottom plate 22 of the insulating plate20 is sandwiched between the lower fastening surfaces 10B of the nuts 10and the upper surface 41A of the sink main body 41 of the heat sink 40to hold the nuts 10, the heat sink 40 and the bottom plate 22 in closecontact.

The properly positioned nuts 10, insulating plate 20 and heat sink 40are set in the first and second block molds 71, 72 without beingdisplaced. More particularly, the heat sink 40 is positioned withrespect to the second block mold 72 by inserting a positioningprojection 72A of the second block mold 72 into the recess 46 of theheat sink 40, as shown in FIG. 16. Further, the insulating plate 20 ispositioned on the heat sink 40 and the nuts 10 are positioned on theinsulating plate 20. Thus, the positioning pins 71A will not displacesufficiently from the bolt tightening holes 11 to break the nuts 10and/or the positioning pins 71A when the positioning pins 71A of thefirst block mold 71 are inserted into the bolt tightening holes 11 ofthe nuts 10. Note that the nuts 10 are accommodated slightly loosely inthe nut accommodating recesses 21 before being fixed by the positioningpins 71A. Hence, slight relative displacements of the positioning pins71A and the bolt tightening holes 11 of the nuts 10 are corrected whenthe first and second block molds 71, 72 are closed so that the nuts 10are fixed to the positioning pins 71A by locating taper surfaces 11Aprovided at the upper inner peripheral edges of the bolt tighteningholes 11 of the nuts 10 at inclined surfaces 71B of the positioning pins71A, as shown in FIG. 16.

Synthetic resin then is injected into a cavity formed by the first andsecond block molds 71, 72 to form the molded resin part 60 as shown inFIG. 16. At this time, the side surfaces of the nuts 10 are held incontact only with the positioning ribs 25 on the inner peripheralsurfaces of the surrounding walls 23 of the insulating plate 20, and thesynthetic resin can flow into the clearances between the inner surfacesof the surrounding walls 23 and the side surfaces of the nuts 10. Thus,the nuts 10, the insulating plate 20 and the molded resin 60 are held inclose contact. Additionally, the nuts 10 and the insulating plate 20 areheld without any chance of backlash.

Finally, the first and second block molds 71, 72 are opened to completethe terminal block.

As described above, the first and second pressing surfaces 28, 29 of theinsulating plate 20 are on the surrounding walls 23 rather than on thebottom plate 22. Thus, there are no indents caused by the ejector pinson the surface of the bottom plate 22 that closely contacts the nuts 10.This enables the nuts 10 and the bottom plate 22 to be held in closecontact and heat can be transferred efficiently from the nuts 10 to theinsulating plate 20. Consequently, heat radiation performance of theterminal block can be improved by efficiently transferring heat from thenuts 10 to the heat sink 40 via the insulating plate 20.

The molded resin 60 is formed with the nuts 10, the insulating plate 20and the heat sink 40 in close contact. Additionally, the nuts 10, theinsulating plate 20 and the heat sink 40 are sandwiched in close contactby the upper and lower covers 61 and 62 of the molded resin 60 toimprove heat transfer from the nuts 10 to the heat sink 40.

The terminal block has the unitary matrix of resin 60 holding the nuts10, the insulating plate 20 and the heat sink 40 at correct positions.Thus, an insulating property between the nuts 10 and the heat sink 40 isensured reliably.

The invention is not limited to the above described and illustratedembodiment. For example, the following embodiments also are included inthe scope of the invention.

The pressing portion is composed of the upper end surfaces of thesurrounding walls 23 and the pressing projections 27 in this embodiment.However, the invention is not limited to such a construction. Forexample, the pressing portion may be composed only of the upper endsurfaces of the surrounding walls 23.

The pressing portion is composed of the upper end surfaces of thesurrounding walls 23 and the pressing projections 27 and the upper endsurfaces of the partition walls 24 in this embodiment. However, thepressing portion may be composed of the bottom surfaces of the boltescaping recesses 26.

The pressing portion is composed of the upper end surfaces of thesurrounding walls 23 and the pressing projections 27 and the upper endsurfaces of the partition walls 24 in this embodiment. However, thepressing portion may be composed of projections provided on outerperipheral parts of the nut accommodating recesses 21 and can be pressedby the ejector pins.

What is claimed is:
 1. A terminal block comprising: an electricallyinsulating plate made of synthetic resin and having at least one nutaccommodating recess including a bottom plate and at least onesurrounding wall extending from the bottom plate and surrounding the nutaccommodating recess, at least one pressing portion formed on an end ofthe surrounding wall opposite the bottom plate; at least one nutaccommodated in the nut accommodating recess and having a fasteningsurface in surface contact with the bottom plate of the nutaccommodating recess, the nut further having an outer peripherysurrounded by the surrounding wall; a heat sink engaging a surface ofthe bottom plate opposite the nut; and a molded resin part surroundingparts of the insulating plate, the heat sink and the nut and holding theinsulating plate sandwiched between the nut and the heat sink.
 2. Theterminal block of claim 1, wherein a plurality of the pressing portionsare formed intermittently on the surrounding wall.
 3. The terminal blockof claim 1, further comprising positioning ribs are provided on theinner surface of the surrounding wall, the positioning ribs extendingsubstantially away from the bottom plate and being engageable with sidesurfaces of the nut.
 4. The terminal block of claim 3, wherein thepositioning ribs are formed to reinforce the surrounding wall oversubstantially an entire height thereof.
 5. The terminal block of claim1, wherein an inner peripheral shape of the surrounding wallsubstantially conforms to an outer peripheral shape of the nut.
 6. Theterminal block of claim 1, wherein the at least one nut accommodatingrecess comprises a plurality of nut accommodating recesses, and the atleast one nut comprises a plurality of the nuts accommodatedrespectively in the nut accommodating recesses; and the surrounding wallincludes at least one partition wall between the nuts.
 7. The terminalblock of claim 6, wherein the partition wall is higher than the nuts. 8.The terminal block of claim 7, wherein the partition wall has a heightthat is more than about 1.5 times higher from the bottom plate thanparts of the surrounding walls that are not between the nuts.
 9. Theinsulating plate of claim 1, wherein the heat sink has a recess forpositioning the terminal block in a mold.
 10. The terminal block ofclaim 1, wherein the synthetic resin of the insulating plate has acontent of glass and talc of between about 50% and about 75%.